基于模型试验的桩周土压力

Soil pressure induced by pile driving based on model test

通过模型试验研究了锤击沉桩过程中挤土桩的径向土压力.通过与静压沉桩的研究结果进行比较,发现这两种沉桩方式引起的径向土压力规律相似:当桩尖向下刺入接近测点时,径向土压力急剧增长;当桩尖尚未刺入测点深度时,测点处的径向土压力就已提前达到峰值;当桩尖继续下沉到测点以下时,测点处的径向土压力又急剧减小;两种沉桩行为引起的径向土压力峰值随深度变化均呈近似线性增长.锤击沉桩和静压沉桩的不同之处在于锤击沉桩的桩周土压力受锤击荷载扰动较大,所以径向土压力曲线相比静压沉桩曲线有较大波动.在砂土密实度相似的情况下,位于同一测点处的静压沉桩的桩周土压力数值明显高于锤击沉桩.

The paper presents laboratory measurements of soil radial stress obtained in two parallel pile driving tests. The tests were designed to impose two modes of load to investigate the underlying mechanism of the radial stress buildup. Analyses on the test results indicated that soil pressure reached a peak before the pile＇s tip reached the depth of the pressure sensor. The buildup of soil pressure was closely related to the penetration depth of the pile. The soil pressure measured by the pressure sensors increased slowly and then dissipated during the pile installation process. Peak radial stress buildup in the vicinity of the pile tip remained higher than that in other places. In general, the peak radial stress reduced quickly in response to dynamic loading compared with the results obtained from press-in loading.